Examples of existing therapeutic agents for hypertension include a variety of neuroleptics acting on the regulation system associated with neural factors, ACE inhibitors acting on the regulation system related to liquid factors, AT acceptor antagonists, Ca antagonists related to the regulation system associated with substances derived from the vascular endothelial, and antihypertensive diuretics related to the hemoral modulation system in the kidneys. These therapeutic agents are used primarily for treating serious hypertensive patients at medicinal institutions. Under present circumstances, however, such medicines for hypertension are forcing the patients to bear heavy burdens due to adverse side effects thereof, though their effectiveness is satisfactory.
Meanwhile, an alimentary therapy, an exercise therapy and general therapies for the improvements of lifestyle such as restrictions of drinking and smoking are widely employed for patient ranging from high normal blood-pressure patients, including mildly hypertensive patients, to severely hypertensive patients. As the importance of general therapies is increasingly acknowledged, the importance of improved dietary life continues to be talked about especially. There are a number of foods known as having hypotensive effects. Intensive searches for antihypertensive materials derived from food have conventionally been conducted, and many effective ingredients have been isolated and identified so far.
Among them, chlorogenic acids, caffeic acids, ferulic acids, which are contained in foods such as coffee, have been reported to show excellent hypertensive effects (Patent Documents 1 to 3). However, coffee beverages known to contain chlorogenic acids in large quantity are also reported to have no plainly recognizable hypotensive effects and tend to increase the blood pressure to the contrary (Non-patent Document 1).    [Patent Document 1] JP-A-2002-363075    [Patent Document 2] JP-A-2002-22062    [Patent Document 3] JP-A-2002-053464    [Non-patent Document 1] Eur. J. Clin. Nutr., 53 (11), 831 (1999).